For the production of an olefin polymer by polymerizing an olefin in the presence of a catalyst, a method has been proposed wherein a catalyst comprising (1) metallocene and (2) aluminoxane is employed (Japanese Unexamined Patent Publications No. 019309/1983 and No. 167307/1990). According to the polymerization method using such a catalyst, the polymerization activities per transition metal are very high as compared with a method of using a conventional Ziegler-Natta catalyst comprising a titanium compound or a vanadium compound and an organic aluminum compound, and it is thereby possible to obtain a polymer having a narrow molecular weight distribution. However, in order to obtain adequate polymerization activities by means of such a catalyst, a large amount of aluminoxane is required, and the polymerization activities per aluminum are low, such being uneconomical. Besides, it is necessary to remove the catalyst residue from the formed polymer.
On the other hand, a method has been proposed wherein polymerization of an olefin is conducted by means of a catalyst having one or both of the above transition metal compound and the aluminoxane carried on an inorganic oxide such as silica or alumina (Japanese Unexamined Patent Publications Nos. 108610/1986, 135408/1985, 296008/1986, 74412/1991 and No. 74415/1991).
Further, a method has been proposed wherein polymerization of an olefin is conducted by means of a catalyst having one or both of the above transition metal compound and an organic aluminum compound carried on an inorganic oxide such as silica or alumina or on an organic material (Japanese Unexamined Patent Publications Nos. 101303/1989, 207303/1989, 234709/1991 and 234710/1991 and Japanese PCT Publication No. 501869/1991).
However, by these methods, the polymerization activities per aluminum are still inadequate, and the amount of the catalyst residue in the product is not negligible.